Signaling system



Dec. 23, 1924. 1,520,098

J. F. TOOMEY SIGNALING SYSTEM Filed April 22, 1924 .IIHII- J1? 150mg ATTORNEY Patented Dec. 23, 19214.

UNITED OFFICE.

JOHN F. TOOMEY, OF NEW YORK, N. Y., ASSIGNOR TO AMERICAN TELEPHONE AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

' SIGNALING SYSTEM.

Application filed April 22, 1924. Serial No. 708,269.

To all whom it may concern:

Be it known that I, J OHN F. TOOMEY, residing at New York, in the county of New York and State of New York, have invented certain Improvements in Signaling Systems, of which the following is a specification.

This invention relates to transmission circuits and more particularly to improvements in signaling arrangements associated therewith.

One of the cardinal features of the arrangements of the invention consists in the provision in the circuits of the signaling relays of a discharge tube, such for example as a neon tube, or any tube filled with gas having the properties that under normal conditions it will present an open circuit to currents but when subjected to a critical voltage will break down and thus present a closed circuit for the associated relay arrangements. The tube in its normal condition will not be affected or break down from the usual message currents transmitted over the circuit and the signaling path will remain open. However, when a high enough voltage, such as the voltage of the currents used for signaling, is applied to the line, the tube will breakdown and the discharge which will take place in the tube closes the normally open signaling circuit. -The arrangements of the invention afford the ime portant advantage that any number of signaling relays may be bridged across a transmission circuit without in any way impairing its transmission efliciency because the circuits of the signaling relays or devices will be open at the tubes except during the signaling interval and hence will present an infinite impedance across the line. Furthermore, the arrangements of the invention permit the use of many desirable selective signaling features which'would otherwise be difiicult and expensive to obtain. Other features and objects of the invention will appear more fully from the following detailed description thereof. r

In the drawing is illustrated a circuit diagram of'a toll line providing selective signaling between two stations in which the various features of the invention are illustrated. 1

In the drawing is shown a transmission line, such as the toll line "L, interconnecting two stations A and B. The line L terminates at station A in the jacks J and J' which might be located at different positions. Associated with each of the acks are provided the signal lamps L and L A sleeve circuit 3 is common to both jacks and includes the relays 4: and 5. Relay 5 is a cut-off relay and relay 4 controls the circuit of a signaling relay 7. Connected in series with relay 7 is the discharge tube 6, such for example as a neon tube. The discharge tube 6 is filled with a gas such that it will normally not be affected by the ordinary telephone currents transmitted over line L when it is bridged across said line. However, when the signaling currents of higher volt-age are applied to the line this voltage will cause the discharge tube to break down and the ensuing discharge 'willcause a circuit to be closed through relay 7. This presents a distinctadvantage in a long distance line such as shown in that a'signaling relay such as 7 may be bridged across the .circuit and will in no way impair the transmission of the telephonic currents as the signaling circuit 'will be normally of infinite impedence as bridged across said line. number of signaling relays which may in this manner he bridged across the circuit is not limited. The relay 7 in the case shown controls the bridging across the line of a resistance 9 for purposes to be pointed out hereinafter. Bridged across line L are the signaling relays 1 and 2. Relay 1 is marginal and will only operate on signaling current of a predetermined strength while relay 2 will operate on'all of the signaling currents utilized. Relays 1 and 2 control relay 10- and 11 which in turn control relays 12 and. '13 to operate the signal lamps L and L as will be pointed out in detail hereinafter. Adapted to cooperate with the jacks J and J 2 is the plug P of a toll co-rd,,only a portion of which is shown. In the toll cord is provided a ringing key K whereby a source of signaling current may be applied to the line. This signaling current will be of sufficient voltage to cause the discharge tubes, such as 6,-to operate. At'station B' are provided arrangements identical with those at station A. Accordingly, like parts have. been designated by like reference characters with the added designation of prime.

The operation of the arrangements is as follows: If the operator at station A desires to signal one of the positions at station B the plug P of the toll cord will be inserted The \ in one of the jacks, such as jack J A cirsignaling current to the conductors of the bridged across the line conductors.

line L, whichwill be transmitted to station B- and thence -through relays 1 and 2 This signaling current will operate both the relays 1 and 2, which will pull up their armatures and open the normally closed circuits through relays 11 .and 10 thereby causing these relays to release. The release of relay 10 will cause ground to be applied to the make contact of relay 10, through the Winding of relay 12, to battery, thereby operating relay 12. The release of relay 10' will remove the ground ordinarily ap plied to the armature of relay 11 so that the release of relay 11' will not cause relay 13f to operate at this time. The operation of relay 12 will connect battery from its righthand armature and contact to conductor 21 and thence to the signal lamp L,. Accordingly the signal lamp L at the position at which jack J" is located may be lighted by the above operations. A locking circuit for relay 12' will be closed from ground, armature and contact of relay 5, conductor 20,

' left-hand armature and contact of relay 12,

Winding of relay 12, to battery and ground.

If the operator at station A desires to signal one of the other positions at station B such for example, as the lamp L is located, the p ug P will be inserted in jack 'J and the key K will be thrown. The relay 4 is included in the sleeve circuit closed by this operation and it will be operated as well as the cut-off relay 5. The operation of relay 4 will bridge across the line conductors the circuit including the dischar e tube 6 and the relay 7. The voltage of t e signaling current applied to the line bythe operation of key K is sufficiently great as that tube 6 will break down and the ensuing discharge taking place therein will allow the signaling current to flow therethrou h and through the winding of relay 7 and t us cause relay 7- to operate. ;It is ointed out again that the voltage of the te ephonic currents transmitted over the line conductors is not sufliciently great to cause a discharge to take place in the tube 6 so as to operate it. The operation of relay 7 will -bridgeacross the line. conductors the circuit 8 which includes a resistance 9. v Accordingly, a portion of the signaling current will be shuntedover circuit 8 and resistance 9 and thesignaling current transmitted on to station B will be materially reduced. This reduced signaling current will .the circuit of relay 11 and release 'it.

osition at which be transmitted through relays 1' and 2. However, the strength of the signaling current will be so reduced that relay 1 which is marginal will not be operated thereby but relay 2 will be operated. Relay 2 will 0 in is will allow the following circuit to be completed,fro1n ground, lower contact of relay 10, armature and upper contact of relay 11, winding of relay 18, to battery and ground. This willoperate relay 13 which will pull up its armatures and close a circuit from battery, left-hand armature and contact of relay 13, conductor 22, to lamp L thereby operating lamp L located at the position at which jack J is located. A locking circuit'for relay 13 will also be closed fromgrou'nd, armature and contact of relay 5, conductor 20, right-hand armature and contact of relay 13, to battery and ground. With such an arrangement the operator at station A may selectively signal any of the positions at station B.

While an arrangement has been shown whereby the discharge tube and signaling relay 7 indirectly control signaling apparatus at a distant station, nevertheless, the signaling relay, 7 might well be utilized to directly control other types of signaling apparatus. It is also pointed out that selectivity in signaling from the point of view of the direction of the current flow may also be attained by-employing the arrangements otthe invention, such as a discharge tube and a signaling relay bridged across the line conductors, for while the voltage applied at station A and flowing toward station B might be high enough to break down and operate the tube at station A, nevertheless, the same-signaling voltage applied at station B and flowing'toward station A by the time it traversed a long distance line and reached station A would be so reduced that it would not'operate the discharge tube at A. Hence the tube at station Awould operate with current flowing in one direction but not with'current flowing from the other direction.

Accordingly, while the arrangements of the invention have been disclosed as emplied currents of relatively low voltage and currents of higher voltage, and a circuit bridged across said transmission line including signaling means and a discharge tube, said discharge tube being of such construction that it will maintain said bridged circu1t open when subjected to said low volt circuit when subjected to said higher voltages.

2. A transmission line to which are applied telephonic currents of relatively low voltage and signaling currents of higher voltage, and a circuit bridged across said transmission line including signaling means and a discharge tube in series, said dlscharge tube being of such construction that it Wlll not operate when subjected to said low voltage currents and hence will cause said bridged cncuit to present substantially an infinite impedance across said transmission line and will break down and operate when subjected to said currents of higher voltage and thus close said bridged circuit for operating said signaling means.

3. A transmission line interconnecting two stations, signaling devices and signaling relays at each of said stations, said signaling relays at each station being responsive to currents of different strengths for selective- 1y operating the signaling devices thereat, means at one of'said stations for applying to said line telephonic currents of relatively low voltage and signaling currents of higher voltage, and means at one of said stations ,for varying the strength of the signaling currents transmitted over said line, said means comprising a circuit adapted to be bridged across said transmission line and including in series a relay and a discharge tube, said discharge tube being of such construction that it will maintain said bridged circuit open when subjected to said low voltages and will operate to complete said bridged circuit when subjected to said higher voltages, and

means controlled by said relay for bridging an impedance across said line.

4. A. transmission line interconnecting two stations, signaling devices and signaling relays at each of said stations, said signaling relays at each station being responsive to currents of difi'erent strengths for selectively operating the signaling devices thereat, means at one of said stations for applying to said line telephonic currents of relatively low voltage and si naling currents of higher voltage, means at one of said stations for varying the strength of the signaling current transmitted over said line, said means comprising a circuitadapted to be bridged acrbss said transmission line, and selective means at said station for bridging said circuit across said line, said bridged circuit in cluding in series a relay and a discharge tube, said discharge tube being of such construction that it normally presents an open circuit when subjected to said relatively low voltages but will operate and present a closed circuit when subjected to said higher voltages, and means controlled by said relay for bridging an impedance across said line.

- 5. A transmission line interconnecting two stations, signaling devices at each of said stations, means at one of said stations for applying to said line telephonic currents of relatively low voltage and signaling currents of higher voltage. a circuit bridged across said line at said station and including in series a discharge tube and a relay, said discharge tube being of such construction that it normally presents an open circuit when subjected to said relatively low voltages and operates to presenta closed circuit when subjected to said higher voltages, and means controlled by said relay for controlling said signaling devices at said distant station.

In testimony whereof, I have signed my name to this specification this 19th day of April, 1924.

JOHN F. TOOMEY. v 

